Anatomical investigation of the bone morphology of the anterior talofibular ligament attachment of fibula

Hitomi Fujishiro¹, Akimoto Nimura², Mizuki Azumaya¹, Soichi Hattori³, ⁴, Osamu Hoshi¹, Keiichi Akita³

¹Department of Pathology and Anatomical Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan; ²Department of Functional Joint Anatomy, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan; ³Department of Clinical Anatomy, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan; ⁴Department of Sports Medicine, Kameda Medical Center, Chiba, Japan

Objective: Anterior talofibular ligament (ATFL) is the most injured due to ankle sprain. Anatomical knowledge of the bony landmarks around the ATFL attachment to the distal fibula is necessary to ensure anatomically precise surgery and ultrasound imaging of the ATFL. The purpose of the present study was to anatomically analyze the ATFL attachment to the fibula in terms of bone morphology and attachment structures.
Methods: First, we used micro-computed tomography to examine 36 feet. Following the exclusion of 9 feet due to deformities, the remaining 27 feet were used for chemically debrided bone analysis and macroscopic and histological observations. Ten feet were of living specimens were observed using ultrasonography.
Results: We identified that a bony ridge was present at the boundary between attachments of the ATFL and calcaneofibular ligament (CFL) to the fibula. Based on a distinction in fiber orientation, these two attachments could be recognized. Histologically, the ATFL was attached to the anterodistal part of the fibula via fibrocartilage that was located anterior to the bony ridge bordering the CFL attachment. The bony ridge and hyperechoic fibrillar pattern of the ATFL could be visualized using in vivo specimens. We determined that the bony ridge matched the posterior margin of the ATFL attachment. This ridge was clearly visible, and the superior fibers of the ATFL were anterior to it.
Conclusion: Combining this bony ridge and the fibrillar pattern of the ATFL could make it a useful marker for ultrasound imaging of the ATFL attachment.

Keywords: ankle; fibula; lateral ligament; ultrasonography